The two natural resources necessary for the production of manufactured goods are raw materials and energy. Both are available in vast quantities amongst the asteroids. Power is provided by vast solar generators and the asteroids are mined for materials. This abundance enables the huge level of industrial activity common across the Belt. The factory complexes in the Belt far exceed even the scale of industrialisation of Luna. Among the citizens of the various poleis and clusters are private individuals who have industrial capacities greater than the smaller of the old nation-states.
At the core of the Belt industrial machine are the mining Swarms. There are hundreds of Swarms, and each may contain thousands of self-replicating drones. The drones are extremely sophisticated devices. Each is as mobile as a singleship, with propulsion by fusion and ion drives. The activities of a Swarm are controlled by network intelligences distributed across its members. The larger Swarms are capable of disassembling entire planetoids and converting its ores into component materials. Specialist constructor drones can then build products as large and complex as habitat Cylinders or torchships.
As an example of the abundance of raw materials in the Belt, consider mining the entire surface of the Earth to a depth of 3km (certainly very much more than would be reasonable). This would yield a cube of material 1150km across. In contrast, mining Ceres and Vesta would yield a cube 1600km on a side. Of course, these two asteroids contain only a fraction of the highly accessible ores in the Belt; mining it all would yield perhaps eight times that given by the hypothetical mining of Earth. Furthermore, most of the Belt ores are contained in fairly small asteroids and so mining it would be remarkably easy. It is clear that the potential for industrial development of the Belt dwarfs that of the Earth, Moon and Mars combined.
The construction and expansion of habitats requires atmospheric gases and water for the biosphere. Limited quantities of both are obtained from the breakdown of minerals found in the asteroids, but most are imported. The primary sources of water are the icy chunks of the rings of Saturn and Jupiter's Galilean moons, whilst atmospheric nitrogen is obtained from the distilleries on Titan.
The future of Ad Astra